My dad has bought the 25.3'' E ink monitor from Dasung. From what he tells, it does not have a backlight and is itself to dark for his taste outside of middle of the day. Maybe it will be better during summer or in bright condition but sitting further away from these devices may require more than just reflectiveness for some users.
That's kinda the point of these things, to not be backlit; you're supposed to provide the needed amount of light yourself.
Indeed, from the description it sounds like their work setup doesn't have enough ambient light for confortable reading conditions.